Solid solutions of the form, NaxK1-xNa1.4Zr1.3Mg0.7(PO4)3, were prepared from end-members with NASICON-type structures. It was found that cationic substitution improved the conductivity, which reached a maximum value when x was equal to 0.7. For each composition, the activation energy was obtained from an Arrhenius plots and was fairly constant as a function of x. The a-parameter was also fairly constant as a function of x, while the c-parameter exhibited a maximum when x was equal to 0.7.

N.Inoue, Y.Yuasa, T.Nakanishi: Solid State Ionics, 1996, 86-88[1], 69-72